Rock drill and like implement



NOV, 2%, H E WARSOP ROCK DRILL AND LIKE IMPLEMENT Filed May 20, 1951 Patented Nov. 20, 1934 UNITED STATES PATENT OFFICE Application May 20, 1931, Serial No. 538,794 In Great Britain November 19, 1930 4 Claims.

This invention relates to rock drills, hammers, caulking and riveting machines and like percussive tools and has for its object to devise an improved method of operating the same which will obviate the necessity for the usual expensive compressed air plant with its long lines of tubing and other attendant disadvantages.

, A further advantage of the invention lies in the fact that by its means I may provide a selfcontained and readily portable tool embodying its power supply means in the same unit.

The invention consists in a percussive tool of the kind referred to operated by an internal combustion engine.

The invention also consists in a percussive tool of the kind referred to operated by an internal combustion engine and having in addition to the engine piston an auxiliary or free piston attached to or adapted to operate upon the tool.

The invention also consists in a percussive tool of the above character in which the auxiliary piston is moved outward to operate the tool by the explosion pressure and is returned by pressure fluid supplied from the engine cylinder.

Further features of the invention will be apparent from the description given hereafter.

The accompanying drawing illustrates one mode of carrying out the invention.

Figure 1 is a side elevation partly in section of one convenient form of rock drill constructed and operating in accordance with the invention, and

Figure 2 is a front elevation partly in section of the tool shewn in Figure 1.

In carrying my invention into effect in one convenient manner as, for example, in its application to a rock drill and as illustrated in Figures 1 and 2 I provide an internal combustion engine a. of suitable form and construction and operating upon a convenient cycle and of a power capacity suited to the nature of the work which the tool is required to perform.

The conventional cylinder head of such internal combustion engine is replaced by a cylinder 1) co-axial with the engine cylinder and of differen- 5 tial diameters adapted to take a differential piston c hereinbefore referred to as the auxiliary or free piston.

The piston c is formed integral with or rigidly secured to a piston rod d working in an extension of the cylinder and either secured to or adapted to operate upon the tool e which may be of appropriate form having regard to the nature of the work which it is to carry out and which may be arranged in any suitable holder or otherwise disposed in accordance with current or desired practice.

The internal combustion engine is fitted with the usual inlet and exhaust valves which may be automatic or may be operated by suitable gearing and there mayalso be provided the usual carburettor f, spark plug g, magneto fitted within the engine fly-wheel h or otherwise suitably arranged and any other appurtenances or accessories common in internal combustion engine practice or indicated as'necessary or desirable in connection with any particular installation required.

In the particular construction illustrated the charge is admitted to the space between the main engine piston and the auxiliary piston and. is fired in said space so that the auxiliary piston receives powerful impulses at the same time as the engine piston and their rapidity can be varied by varying the speed of the engine, the said impulses being as hereinbefore indicated transmitted to the operative tool of the machine.

For the purpose of effecting the return of the tool preparatory to the next working stroke or blow I preferably employ fluid pressure supplied from the engine cylinder and in the particular construction illustrated this is accomplished by forming the auxiliary cylinder c of differential diameters so that the outer part c is of larger area than the inner or working face, and I connect the main engine cylinder with the outer larger part of the cylinder b by means of a port or passage 1' arranged to be opened by the main engine piston prior to exhaust so that the pressure fluid from the engine cylinder is admitted to the under face of the auxiliary piston which being of larger area than the inner face ensures the return of the auxiliary piston.

The port 12 may be arranged to be closed by means of a valve 70 at starting and the ignition may also be retarded to facilitate such starting. With the arrangement described the engine may be operated upon either the two-stroke or fourstroke cycle and the position of the free piston cylinder may be varied relatively to the main cylinder as, for example, in some cases where it may be found convenient to arrange these two cylinders at an inclination to one another instead of being in alignment as in the construction shewn. 7

In some cases I may arrange to effect the re:- turn movement of the free piston by means of the exhaust gases by, for example, connecting the larger auxiliary cylinder space to a by-pass passage 1 associate with the exhaust port 0.

If preferred the lateral port in connection with the communicating passage i may be controlled by a valve (instead of by the main engine piston) so that the action of the auxiliary piston may be controlled without stopping the engine, this mode of control being essential, for example, in the case where the invention is applied to a hammer. In such cases the control may take the form of a sleeve valve p surrounding the piston and operated by an eccentric cam r on a shaft s extending through the piston wall. Alternatively any other suitable form of control valve may be provided.

When applying the invention to a drill of the kind shewn in the drawing air cooling of the engine by means of the usual radiating fins upon the cylinder would probably suffice but in some cases it may be necessary or desirable to arrange for water cooling in which event any suitable means may be adopted for the purpose.

Further, in any modification of the invention it may be convenient to arrange for the tool e to be given a slight angular movement at each stroke or blow and any convenient means may be adopted for attaining this object while in some cases also it may be desirable to utilize the pressure fluid for clearing the hole in which the tool is operating, in which case such fluid may be conveniently supplied from the auxiliary cylinder through a port or ports formed in the auxiliary piston rod and/or tool shank or direct through a suitable port or ports from the engine cylinder.

It will be seen that by means of the invention I have provided a very compact self-contained form of tool embodying its own power supply thus eliminating the necessity for any expensive compressed air plant with its long length of tubing and other inconveniences while at the same time the tool may be made readily portable so that it may be conveniently operated in any particular situation and rapidly transported from place to place. The self-contained unit is further exemplified in the particular construction shewn in the drawing by the fact that the machine may carry its own fuel supply tank such as is shewn at Z just below the handle m by means of which the tool may be manipulated and carried and the operative parts of the tool may be enclosed by a jacket or casing 11 whereby such parts may be protected from ingress of dirt or other foreign matter and from injury during use.

An important feature of the invention is the combination with an internal combustion engine of a mechanically free piston controlled entirely by the gases under pressure and adapted to operate the tool or tools. The engine itself performs no work other than that needed to drive the fan, magneto, and any other accessories provided but by the medium of the free piston the power of each working stroke is delivered-direct to the tool or tools, and the device is therefore very much more efiicient than the usual internal combustion engine-compressed air system with its large losses.

It will be understood that the foregoing details of construction are given purely by Way of illustration to indicate the nature of the invention and one method of carrying the same into eifect, and the invention is therefore not to be considered as being limited in its scope by the details of construction described since I may vary the form and arrangement of internal combustion engine and the means adopted for enabling the same to operate upon the drill or other tool depending upon the character of tool to which the invention is to be applied and the nature of the duties which it may be called on to fulfill.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:--

1. An impact tool of the type operated by an internal combustion engine, comprising an internal combustion engine cylinder and a piston therein, an auxiliary cylinder of differential diam'eters communicating at its smaller end with the engine cylinder, a head at the larger end of the auxiliary cylinder, a mechanically free piston of corresponding differential diameters movable in the auxiliary cylinder, and a conduit controlled by the engine piston and connecting the engine cylinder with the portion of the auxiliary cylinder of larger diameter.

2. An impact tool as claimed in claim 1, characterized in that said conduit communicates with the larger part of the auxiliary cylinder between the piston therein and said head.

3. An impact tool as claimed in claim 1, characterized by the provision of a valve interposed in said conduit for controlling the passage therethrough.

4. An impact tool as claimed in claim 1, characterized in that the movement of the mechanically free piston is limited, on the one hand, by said head, and on the other hand, by the shoulder defined by the differential diameters of the auxiliary piston.

HENRY ERNEST WARSOP. 

